Fiber optic sensing systems may be used to monitor downhole physical parameters such as vibrations, acoustics, pressure, and temperature. One example sensing system is referred to as distributed sensing. In a distributed sensing system, an interrogation beam is conveyed along an optical fiber, and interferometric techniques are applied to perform phase analysis of backscattered light. The phase information of backscattered light can be correlated with physical parameters at points along the optical fiber. However, recovering phase information accurately is difficult in part due to phase wrapping ambiguities. Some previous efforts to account for phase wrapping use fringe counters to count 2π phase increments. However, existing fringe counters suffer from inaccuracies if a phase change of more than π occurs between a current phase measurement and a previous phase measurement.
It should be understood, however, that the specific embodiments given in the drawings and detailed description thereto do not limit the disclosure. On the contrary, they provide the foundation for one of ordinary skill to discern the alternative forms, equivalents, and modifications that are encompassed together with one or more of the given embodiments in the scope of the appended claims.